A slang term for Ecstacy (MDMA) commonly used in the San Francisco Bay area of the United States. However, the slang term has become widely popular by the song "Don't Drop That Thun Thun" by Finatticz.

A: "You better not drop that thun thun."

B: "But, if I drop it, I can just pick it up, grab a bad bitch, and head to the cut!"